Rotary pump



March 26, 1946. FOWLER 2,397,098

r ROTARY PUMP Filed Jan. e, 1944 "i J. a I

Patented Mar. 26, i946 Elbert Fowler, Mount Vernon, N. Y.

Application January-d, liihsferial No. 517,,l6ll

(Cl. Na r-133) 2 Claims.

This invention relates, asin'dicat ed, to rotary pumps but has reference more particularly to rotary pumps of the sliding vane type.

In'my prior Patent 2,347,944, of May 2, 19%, I have described a rotary pump, of the sliding'vane type which is suitable for air or gas compressors or vacuum pumps, said pump comprising'a body having a circular bore into which a stator is fitted and secured against rotation. The stator has a bore, the cross-section of which consists of two diametrically opposed truly circular arcs of unequal radii, whose center is the center of the rotor, and vane extending and retracting curves joining adjacentends of said arcs, said curves being generated curves determined by the equation 1 wherein R is the distance from the center of the wherein a is the angle between a line joining the,

center of the rotor and an end of the are of smaller radius and a line joining the center of the rotor and the point on the curve, the locationor position of which is to be determined, and a is the angle subtended by said arc. The angle subtended by one of the arcs, as described in the aforesaid patent, is the sameas that subtended by the other arc.

, The function of the aforesaid arcs, as described in the aforesaid patent, is to improve the seal between the rotor and the stator at the points where the arcs are located, and the arcs, as.

shown in the drawings in said patent, are rather short, extending for about 10 degrees.

I have discovered, however, that the indexing operations in machining the cams for making the bore of the stator can be greatly simplified by omission of the circular arc portions of the bore, and without appreciablitafiecting the sub-- stantially smooth pulsationless flow oi air or other fluid through the pump.

The present invention, in other words, is concerned primarily with the provision oi a pump of the character described, in which the arcuate sealing portions of the pump bore areoruittedand each of the vane retracting and extending curves is extended through an angle of 180 degrees.

In order to better understand the nature of the invention, a pump havingincorporated therein the, aforesaid vane extending and retracting curves will now be described, reference being had to the accompanyingdrawing, forming a part of the present specification, and wherein Fig. 1 is a view partly in elevation and partly .in section, of a pump incorporating the aforesaid curves in the bore thereof;

Fig. 2 is a transverse cross-sectional view, takenon the line 22 of Fig. l, and

Fig. 31s an enlarged cross=sectional view of the bore of the pump shown in Fig. 1.

Referring to the drawing, it will be seen that a rotary pump constructed in accordance with the invention comprises'a body 5 having a-circular bore 2 into which a stator d is fitted and secured against rotation relatively to the body by means of a key 6. The stator is secured against endw'ise movement in the body 3 by means of thrust bearings ii and 6, which bearings also serve as radialor journal bearings for the rotor 'i or the pump. The rotor t projects beyond one end of the pump body and is provided with a splined' extension t, ,whereby the rotor may be driven. 1 a

The rotor i is rotatable about the center or axis 0, and is provided with slots ii at right angles to each other and with vanes id and i l which are slldable radially in, these slots. The vanes iii and ii are cut away as at 12 to clear each other, the cut away portions being of suficient length to permit the maximum radial movement of the vanes without interference with each other. The outer ends of the vanes are preferably fitted with rocker seals it, the function of which will be readily understood by those skilled in the art to which this invention relates.

The combined lengths of the vanes and rocker seals is greater-than the external diameter of the rotor, and the vanes" which term will here- 4 the stator at any point in the rotation of the rotor, the interior of the stator cannot be. circular, but consists, in this case, of two identical 2 2,897,098 curves, which are symmetrical with respect to a vertical radial plane A -B, which passes through the axis 0. Each of these curves is a generated curve, which is represented by the equation wherein R is the distance from the center O to the point on the curve, the location of which is to be determined, 11 is the radius of the rotor plus running clearance, at the point F where the-rotor is in contact with the stator, h is the excess of 1 the .vane length over the rotor diameter, and 0 is the angle determined from the equation which is referred to in the aforesaid patent, a being the angle of the sealing arcs. Since, in

bore to the right of the radial plane AB, since it is symmetrically located relatively to th curve becomes 0' 20 to the left of said plane-is determined or generated in the same manner as the latter.

The pump, as thus described, is particularly adapted'i'or air or gas compressors, or as a vac-.

uum pump, and is characterized by a substantially smooth flow and smooth blade acceleration.

Since the generated curves defining the bore of the stator are symmetrical about a vertical plane (AB) through the center 0 of the rotor, it

iollows that the pump is reversible, insofar as the direction of rotation of the rotor is concerned.

In some cases, where the body of the pump is of a fairly hard metal, the stator may be elimihated, and the generated bore or curve for the rotor formed directl in the pump body. This obvious variation or modification is contemplated by the subioined claims. I

Although I have shown and described a pump having two sliding vanes, it will be understood that this is the preferred number of vanes, al-

though a single vane may be employed, if de- 5 sired. A greater number of vanes than two is undesirable for a number of reasons, among which may be mentioned the weakening of the rotor, due to the necessity of providing slots for the increased number of vanes, and; the diiiiculty 01 providing suiiicient vanev rigidity or strength. where room must be provided tora large number of vanes.

It is to be understood that the form of my invention, herewith shown and-described, is to be taken as a preferredexample of the same. and that various changes in the shape,'size and arrangement of parts may be resorted to, without departing from the spirit or my invention, or the scope of the subjoined claims.

Having thus described my invention, I claim:

1. A rotary pump comprising a pump body having a stator therein, a rotor disposed within said stator and wines slidably mounted in said rotor, said stator having a bore deflned'by two symmetrically disposed vane extending and retracting curves which join each other at a radial plane passing through the axis of said rotor, said curves each extending .for degrees and being generated curves determined by the equation wherein R. is the distance from the center of the rotor to the point on'the curve, the position of which is to be determined, n is the radius of the rotor plus running'clearance, h. is the excess of the vane length over the rotor diameter, and 0 'isthe angle determined from the equation 0%20 wherein 0' is the angle betweenthe portion of said plane a ove the axis of the rotor anda line joining the center of the rotor and the point on the curve, the position of which is to be determined.

2. A rotary pump having a rotor, and vanes 'slidabl'y mounted in said rotor, said pump having a bor'edefined by two symmetrically disposed vane extending and retracting curves which join each other at a radial plane passing through the axis of said rotor, said curves each extending for 180 degrees and being generated'curves determined by the equation wherein R is the distance from the center of the, .rotor to the point on the curve, the position of which is to be determined, n is the radius of the rotor plus running clearance, h is the excess of the vane length over the rotor diameter, and 0 5 said plane above the axis of the rotor and a line joining the center of the rotor and the point on the curve, the position of which is to be determined.

ELBERT FOWLER. 

